‘87 SDL. AC Rebuild Not Satisfactory - Page 2 - PeachParts Mercedes-Benz Forum

Diseasel300 · #16 06-15-2018, 10:24 AM

Refrigerants are fickle. Charge to 36 oz, THEN check pressure, not the other way around. It helps to have a large fan blowing across the condenser. As the refrigerant condenses to a liquid in the condenser, its pressure drops slightly. This is why you can have an overcharged system but still "looks" relatively normal when the pressures are checked. Get a strong light and shine in the sightglass on the filter dryer, I'd bet with the charge you have in it now you've got some pretty strong flashing going on.

Max, the generic "charging chart" referenced above is assuming idle speeds. It isn't perfect, but it'll get you close if you know what you're looking for.

oilslick · #17 07-13-2018, 03:55 PM

After I got the pressures right according to the information I gathered from here and there I still couldn’t get the vent temperature down below 60* at speed. When I would turn on the AC and press the recirculating button I could hear a distinct change in the airflow. I took that to mean that my recirculating door was functioning correctly. I found out that the recirculating door was only opening slightly. I managed to prop the door open for now and the difference is like Summer and Winter. I’m getting 42* with the fan on high at speed (35* with the fan on low at speed). Sitting idling for any length of time the temp will rise to around 45*-49*. I’m satisfied. Case closed!

Diseasel300 · #18 07-13-2018, 06:40 PM

Not too far off from mine. The vacuum solenoid block on mine was suffering from broken solder joints, and also found a broken vacuum line going to the recirculate flaps. Repaired that today and I'm blowing 38-40˚ with fan on max, easily holding 45˚ at idle. It was working well before, but now you can hang meat in there. Having everything working and the charge just perfect is key to frosty A/C, SO enjoyable in the hot summer!